The invention relates to digitizing bar code symbol data.
Bar codes symbols are graphical objects that encode information as alternating dark and light portions, i.e., alternating regions of different light reflectivity, having specific relative widths. Bar code scanners have a wide range of applications, including reading bar code symbols provided on products. From analog electrical signals containing information representative of reflected light from the bar code symbols, the scanners produce digitized electrical signals that are typically fed to computing apparatus for decoding and providing an identification of the product to which the bar code symbol is applied. Examples of bar code symbols and scanners are found in almost every supermarket, convenience store, and department store, as well as in warehouses and factories that use bar code symbols and scanners for inventory and production control.
Bar code scanners include laser scanning bar code readers, which scan the spot of a laser beam across a bar code, and bar code imaging systems, which image the entire bar code onto a sensor (e.g., a CCD).
To decode the information, the bar code scanner must determine the relative widths of the dark and light portions to an effective degree of accuracy. Typically, if the scanner acquires a representation of the bar code symbol in which the symbol is blurred (e.g., due to optical or electrical filtering or being out-of-focus), decoding the information is difficult because the transitions between the dark and light portions (i.e., boundaries between the adjoining regions of different light reflectivity) become indistinct, which complicates the determination of the relative widths.